Effects of environmental factors and predation on benthic communities in headwater streams

Abstract

Structure and composition of benthic macroinvertebrate assemblages were investigated during three consecutive years in six headwater streams that exhibit a high variation in environmental conditions, habitat structure and predatory pressure. We examined whether the abundance of functional feeding groups could be best predicted by the abundance of predators and some habitat and chemical variables. Mean density and biomass of macroinvertebrate functional feeding groups varied significantly throughout the study area. Stepwise multiple regression analyses revealed that both density and biomass of functional feeding groups was influenced primarily by chemical features of water. Shredder biomass and scraper density were also influenced by habitat features, the abundance of scrapers increasing in deeper localities at lower altitudes and with abundant macrophytes. The abundance of predatory invertebrates was related to the density and biomass of benthic prey. An influence of fish predation on invertebrate communities was not observed in the study streams. The finding that benthic communities in undisturbed headwater streams are mainly affected by water chemistry variables irrespective of fish predation and habitat features clearly highlight the sensitivity of functional feeding groups to changes in chemical features and their role as indicators for bioassessment.

Shaping of macroinvertebrate structures in a small fishless lowland stream exposed to anthropopressure, including the environmental conditions

“…Multiple authors provide different answers, and in the opinion of many of them, it mostly depends on the type of reservoir. For example, Nicola et al (2010) claimed that in streams, benthic communities are most affected by water chemistry, and less by fish predation. On the other hand, Williams and Taylor (2003) found a significant influence of fish predations on the density and taxonomic structure of invertebrates in isolated pools of an intermittent stream.…”

“…For example, Choe et al (2014) showed that in the examined regulated watercourse, predatory fish can be the main limiting factor for certain groups of invertebrates. On the other hand, Nicola et al (2010) found that the structures of benthic macroinvertebrates are shaped primarily by water chemism, rather than by the presence of predatory fish. The aim of our study was to determine the impact on the structures of macrozoobenthos in a small field watercourse exerted by abiotic conditions, with the concurrent lack of fish and varied intensity of anthropopressure.…”

Benthic macroinvertebrate community structure and seasonal variation in a neotropical stream in the State of Alagoas, Brazil

“…The canonical correlation analysis showed the influence of water chemistry on the macroinvertebrate community, as aquatic chemistry variables are frequently used to explain variation in benthic communities (Nicola et al 2010). Alkalinity, pH and Dissolved Oxygen were shown as the most important environmental factors, as they were associated to the decomposition of organic matter.…”

“…Therefore, it is essential to understand the relative roles of habitat and water chemistry in structuring macroinvertebrate communities in headwaters (Nicola et al 2010).…”

“…The abundance of stream invertebrates is known to be influenced by environmental conditions such as: hydraulic stress, temperature and water chemistry (Silveira 2004, Cummins et al 2005, Nicola et al 2010, Rosin et al 2010. The dry and rainy season variation is important to determine ecological changes in the tropics (Chukwu & Nwankwo, 2004).…”